The present invention relates generally to a device and method for the treatment of ocular diseases with radiation. Particularly, the device and method will be utilized to deliver a dose of radiation to a portion of the eye globe to treat subretinal neovascularization associated with age-related macular degeneration.
Macular degeneration is a pathologic process associated with subretinal neovascularization. The subretinal neovascularization allows fluid, blood, and lipids to leak beneath the surface of the retina. This leakage has detrimental effects on the health of the globe. For example, this leakage may cause hypoxia, retinal detachment or other eye condition problems. These conditions can cause scarring that will destroy the macular retina. The effect of the scarring on the macular retina can be severe. Specifically, it may cause irreversible loss of central vision.
There are currently two methods for treatment of macular degeneration. These methods utilize lasers to effect closure of subretinal neovascularization. While laser/photocoagulation is effective in closing subretinal neovascularization and preserving visual acuity, laser treatment is only effective in a small subset of patients, and can cause destruction of the overlying retina. The. other laser-assisted treatment utilizes light-activated dyes to close the subretinal neovascular vessels.
A new method utilized in the treatment of macular degeneration is radiation therapy. For example, low levels of ionizing radiation have been used to induce regression of choroidal hemangiomas, to stunt the growth of neovascular component of wounds, to close vascular malformations, and to treat subretinal neovascularization without destruction of the overlying retina. In one method of radiation treatment, the radiation is delivered to the affected area of the globe through the use of disk-like devices called ophthalmic plaques. Plaques are attached to the eye and remain there for a period of typically several days. However, the use of ophthalmic plaque radiation suffers from problems with the devices, localization beneath the macula, slow delivery requiring long treatment times, and fixed aperture sizes due to limitations on the ability to place relatively small objects in position beneath the macula (subretinal neovascularization) target. These side effects may be because these plaques are allowed to stay attached to the eye for a period of time, causing the irradiation of normal ocular tissue throughout the dose period.
Therefore, an improved device and method are needed for the treatment of intraocular neovascularization such as that associated with age-related macular degeneration to prevent scarring and to induce closure of normal blood vessels within the eye. The device of the invention may also have utility in ocular oncology applications.
It is an object of the present invention to provide a device for nonpermanent variable exposures of ionizing radiation to specific places on the eye globe without excessive exposure of the normal ocular structures.
In accordance with the above object and other objects evident from the following description of a preferred embodiment of the invention, an ophthalmic brachytherapy device is provided for treating a diseased area with radiation. The device comprises a handle, an applicator coupled with said handle and adapted to receive a source of radiation with the applicator movable between a first radiation shielding position and a second position wherein radiation is allowed to reach the diseased area, a shield for receiving the applicator, a source of radiation coupled with the applicator, and an actuator for moving the applicator between first and second positions thus moving the radiation source between the two referenced positions (additional positions being optional). The invention also encompasses a method of treating macular degeneration which includes providing a source of radiation; placing the radiation source in an applicator which is movable between stored and treating positions; providing a shield to contain radiation while the applicator is being inserted and positioned; providing a light source proximal the radiation source, and moving the radiation source and the light source from the shielded position into a location proximal the eye globe.
By providing an ophthalmic brachytherapy device and method according to the present invention numerous advantages are realized. These include the provision of light sources both proximal and distal the radiation source for focusing light on the area to be treated. This facilitates precise placement of the radiation.
Another advantage of the present invention is that the radiation source is movable between treating and retracted positions. Shielding is provided in both positions, although to a greater degree in the retracted position thereby minimizing the exposure of normal tissue to the radiation source.
Still another of the advantages of the present invention is that by virtue of the radiation source being extendable and retractable the amount of radiation to which the diseased tissue is exposed may be controlled more precisely by controlling the extent to which the radiation source is extended from the shielding.
Still another advantage of the present invention is the presence of a light source which defines the area to be treated.
By providing an ophthalmic brachytherapy device in accordance with the present invention, numerous advantages are realized. For example, by providing nonpermanent variable exposure to the affected areas, normal ocular tissue will sustain less irradiation.
An additional advantage provided by the present invention is associated with the reduced amount of irradiation of the normal ocular structures during the positioning of the ophthalmic brachytherapy device.